Superfoods could raise cancer risk

Scientists are rethinking the role of antioxidants in foods such as blueberries. Photo / Thinkstock

Fashionable anti-cancer superfoods and supplements do not prevent the disease and may even cause it, according to a scientist who helped discover the structure of DNA.

Dr James Watson said the cure for many cancers will remain elusive unless scientists rethink the role of antioxidants, which include vitamin pills and food such as blueberries and broccoli.

It is widely believed they boost health and fight cancer by mopping up oxygen molecules called free radicals. But Dr Watson argues these may be key to preventing and treating cancer - and depleting the body of them may be counter-productive.

Free radicals not only help keep diseased cells under control, they are also pivotal in making many cancer drugs, as well as radiotherapy, effective, he believes.

Writing in a journal published by the Royal Society, the 84-year-old Nobel laureate stated that antioxidants 'may have caused more cancers than they have prevented'.

"For as long as I have been focused on the curing of cancer, well-intentioned individuals have been consuming antioxidative nutritional supplements as cancer preventatives, if not actual therapies," he said.

"In light of recent data strongly hinting that much of late-stage cancer's untreatability may arise from its possession of too many antioxidants, the time has come to seriously ask whether antioxidant use much more likely causes than prevents cancer."

He said a vast number of studies had found antioxidants including vitamins A, C and E and the mineral selenium, to have 'no obvious effectiveness' in preventing stomach cancer or in lengthening life.

Instead, they seem to slightly shorten the lives of those who take them, and vitamin E may be particularly dangerous.

The American, who describes his theory as among his most important work since the DNA breakthrough with British colleague Francis Crick in 1953, said blueberries may taste good but give no protection against cancer. The study by Dr Watson, based at the Cold Spring Harbor Laboratory in New York, is published in the journal Open Biology.

He has caused uproar in the past with his opinions on race, intelligence, beauty and homosexuality.

Professor Nic Jones, of Cancer Research UK, agreed that studies showed antioxidants were ineffective for cancer prevention in healthy people and can even slightly increase the risk of the disease.

He said vitamins and minerals should be obtained through a healthy and balanced diet.

Broccoli: Tests show cancer-fighting potential through its high sulforaphane levels. Rich in vitamin C, fibre and vitamin K, which helps strengthen bones and aids blood clotting.

Blueberries: Good for age-defying properties. High in vitamin C and cancer-fighting antioxidants that also cut the risk of heart disease.

Sweet Potatoes: High in vitamin A, which keeps skin, eyes and the immune system healthy.

Goji Berries: These raisin-like fruits contain more vitamin C than oranges, more vitamin A than carrots and more iron than steak.

Kiwi Fruit: High levels of polyphenols, the compounds found in red wine that fight heart disease. High antioxidant activity and rich in vitamin C.

Green Tea: Mops up free radicals blamed for cancer, blood clots and hardening of the arteries. May fight obesity and lower 'bad' cholesterol.